class MIME::Type

The definition of one MIME content-type.

Usage

require 'mime/types'

plaintext = MIME::Types['text/plain'].first
# returns [text/plain, text/plain]
text      = plaintext.first
print text.media_type           # => 'text'
print text.sub_type             # => 'plain'

puts text.extensions.join(" ")  # => 'asc txt c cc h hh cpp'

puts text.encoding              # => 8bit
puts text.binary?               # => false
puts text.ascii?                # => true
puts text == 'text/plain'       # => true
puts MIME::Type.simplified('x-appl/x-zip') # => 'appl/zip'

puts MIME::Types.any? { |type|
  type.content_type == 'text/plain'
}                               # => true
puts MIME::Types.all?(&:registered?)
                                # => false

Constants

VERSION

The released version of the mime-types library.

Attributes

content_type[R]

Returns the whole MIME content-type string.

text/plain        => text/plain
x-chemical/x-pdb  => x-chemical/x-pdb
docs[RW]

The documentation for this MIME::Type.

encoding[R]

The encoding (7bit, 8bit, quoted-printable, or base64) required to transport the data of this content type safely across a network, which roughly corresponds to Content-Transfer-Encoding. A value of nil or :default will reset the encoding to the default_encoding for the MIME::Type. Raises ArgumentError if the encoding provided is invalid.

If the encoding is not provided on construction, this will be either ‘quoted-printable’ (for text/* media types) and ‘base64’ for eveything else.

extensions[R]

The list of extensions which are known to be used for this MIME::Type. Non-array values will be coerced into an array with to_a. Array values will be flattened, nil values removed, sorted, and made unique.

media_type[R]

Returns the media type of the simplified MIME::Type.

text/plain        => text
x-chemical/x-pdb  => chemical
raw_media_type[R]

Returns the media type of the unmodified MIME::Type.

text/plain        => text
x-chemical/x-pdb  => x-chemical
raw_sub_type[R]

Returns the media type of the unmodified MIME::Type.

text/plain        => plain
x-chemical/x-pdb  => x-pdb
references[R]

The encoded references URL list for this MIME::Type. See urls for more information.

This was previously called url.

simplified[R]

The MIME types main- and sub-label can both start with x-, which indicates that it is a non-registered name. Of course, after registration this flag can disappear, adds to the confusing proliferation of MIME types. The simplified string has the x- removed and are translated to lowercase.

text/plain        => text/plain
x-chemical/x-pdb  => chemical/pdb
sub_type[R]

Returns the sub-type of the simplified MIME::Type.

text/plain        => plain
x-chemical/x-pdb  => pdb
xrefs[R]

The cross-references list for this MIME::Type.

Public Class Methods

new(content_type) { |self| ... } click to toggle source

Builds a MIME::Type object from the provided MIME Content Type value (e.g., ‘text/plain’ or ‘applicaton/x-eruby’). The constructed object is yielded to an optional block for additional configuration, such as associating extensions and encoding information.

  • When provided a Hash or a MIME::Type, the MIME::Type will be constructed with init_with.

  • When provided an Array, the MIME::Type will be constructed only using the first two elements of the array as the content type and extensions.

  • Otherwise, the #content_type will be used as a string.

# File lib/mime/type.rb, line 90
def initialize(content_type) # :yields self:
  self.system      = nil
  self.obsolete    = false
  self.registered  = nil
  self.use_instead = nil
  self.signature   = nil

  case content_type
  when Hash
    init_with(content_type)
  when Array
    self.content_type = content_type[0]
    self.extensions   = content_type[1] || []
  when MIME::Type
    init_with(content_type.to_h)
  else
    self.content_type = content_type
  end

  self.extensions   ||= []
  self.docs         ||= nil
  self.encoding     ||= :default
  # This value will be deprecated in the future, as it will be an
  # alternative view on #xrefs. Silence an unnecessary warning for now by
  # assigning directly to the instance variable.
  @references       ||= []
  self.xrefs        ||= {}

  yield self if block_given?
end

Public Instance Methods

<=>(other) click to toggle source

Compares the MIME::Type against the exact content type or the simplified type (the simplified type will be used if comparing against something that can be treated as a String with to_s). In comparisons, this is done against the lowercase version of the MIME::Type.

# File lib/mime/type.rb, line 134
def <=>(other)
  if other.respond_to?(:content_type)
    @content_type.downcase <=> other.content_type.downcase
  elsif other.respond_to?(:to_s)
    @simplified <=> MIME::Type.simplified(other.to_s)
  end
end
add_extensions(*ext) click to toggle source

Merge the extensions provided into this MIME::Type. The extensions added will be merged uniquely.

# File lib/mime/type.rb, line 231
def add_extensions(*ext)
  self.extensions = self.extensions + ext
end
ascii?() click to toggle source

MIME types can be specified to be sent across a network in particular formats. This method returns false when the MIME::Type encoding is set to base64.

# File lib/mime/type.rb, line 423
def ascii?
  not binary?
end
binary?() click to toggle source

MIME types can be specified to be sent across a network in particular formats. This method returns true when the MIME::Type encoding is set to base64.

# File lib/mime/type.rb, line 416
def binary?
  BINARY_ENCODINGS.include?(@encoding)
end
complete?() click to toggle source

Returns true if the MIME::Type specifies an extension list, indicating that it is a complete MIME::Type.

# File lib/mime/type.rb, line 455
def complete?
  not @extensions.empty?
end
default_encoding() click to toggle source

Returns the default encoding for the MIME::Type based on the media type.

# File lib/mime/type.rb, line 273
def default_encoding
  (@media_type == 'text') ? 'quoted-printable' : 'base64'
end
eql?(other) click to toggle source

Returns true if the other object is a MIME::Type and the content types match.

# File lib/mime/type.rb, line 183
def eql?(other)
  other.kind_of?(MIME::Type) and self == other
end
from_array(*args) { |t| ... } click to toggle source

Creates a MIME::Type from an array in the form of:

[type-name, [extensions], encoding, system]

extensions, encoding, and system are optional.

MIME::Type.from_array("application/x-ruby", ['rb'], '8bit')
MIME::Type.from_array(["application/x-ruby", ['rb'], '8bit'])

These are equivalent to:

MIME::Type.new('application/x-ruby') do |t|
  t.extensions  = %w(rb)
  t.encoding    = '8bit'
end

This method is deprecated.

# File lib/mime/type.rb, line 580
def from_array(*args) # :yields MIME::Type.new:
  MIME.deprecated(self, __method__)

  # Dereferences the array one level, if necessary.
  args = args.first if args.first.kind_of? Array

  unless args.size.between?(1, 8)
    raise ArgumentError, "Array provided must contain between one and eight elements."
  end

  MIME::Type.new(args.shift) do |t|
    t.extensions, t.encoding, t.system, t.obsolete, t.docs, t.references,
      t.registered = *args
    yield t if block_given?
  end
end
from_hash(hash) { |t| ... } click to toggle source

Creates a MIME::Type from a hash. Keys are case-insensitive, dashes may be replaced with underscores, and the internal Symbol of the lowercase-underscore version can be used as well. That is, Content-Type can be provided as content-type, Content_Type, #content_type, or :content_type.

Known keys are Content-Type, Content-Transfer-Encoding, Extensions, and System.

MIME::Type.from_hash('Content-Type' => 'text/x-yaml',
                     'Content-Transfer-Encoding' => '8bit',
                     'System' => 'linux',
                     'Extensions' => ['yaml', 'yml'])

This is equivalent to:

MIME::Type.new('text/x-yaml') do |t|
  t.encoding    = '8bit'
  t.system      = 'linux'
  t.extensions  = ['yaml', 'yml']
end

This method has been deprecated.

# File lib/mime/type.rb, line 621
def from_hash(hash) # :yields MIME::Type.new:
  MIME.deprecated(self, __method__)
  type = {}
  hash.each_pair do |k, v|
    type[k.to_s.tr('A-Z', 'a-z').gsub(/-/, '_').to_sym] = v
  end

  MIME::Type.new(type[:content_type]) do |t|
    t.extensions  = type[:extensions]
    t.encoding    = type[:content_transfer_encoding]
    t.system      = type[:system]
    t.obsolete    = type[:obsolete]
    t.docs        = type[:docs]
    t.url         = type[:url]
    t.registered  = type[:registered]

    yield t if block_given?
  end
end
from_mime_type(mime_type) click to toggle source

Essentially a copy constructor.

MIME::Type.from_mime_type(plaintext)

is equivalent to:

MIME::Type.new(plaintext.content_type.dup) do |t|
  t.extensions  = plaintext.extensions.dup
  t.system      = plaintext.system.dup
  t.encoding    = plaintext.encoding.dup
end

This method has been deprecated.

# File lib/mime/type.rb, line 654
def from_mime_type(mime_type) # :yields the new MIME::Type:
  MIME.deprecated(self, __method__)
  new(mime_type)
end
like?(other) click to toggle source

Returns true if the simplified type matches the current

# File lib/mime/type.rb, line 122
def like?(other)
  if other.respond_to?(:simplified)
    @simplified == other.simplified
  else
    @simplified == MIME::Type.simplified(other)
  end
end
obsolete?() click to toggle source

Returns true if the media type is obsolete.

# File lib/mime/type.rb, line 288
def obsolete?
  !!@obsolete
end
platform?() click to toggle source

Returns true if the MIME::Type is specific to the current operating system as represented by RUBY_PLATFORM.

This method is deprecated.

# File lib/mime/type.rb, line 448
def platform?
  MIME.deprecated(self, __method__)
  system? and (RUBY_PLATFORM =~ @system)
end
priority_compare(other) click to toggle source

Compares the MIME::Type based on how reliable it is before doing a normal <=> comparison. Used by MIME::Types#[] to sort types. The comparisons involved are:

  1. self.simplified <=> other.simplified (ensures that we don’t try to compare different types)

  2. IANA-registered definitions < other definitions.

  3. Generic definitions < platform definitions.

  4. Complete definitions < incomplete definitions.

  5. Current definitions < obsolete definitions.

  6. Obselete with use-instead references < obsolete without.

  7. Obsolete use-instead definitions are compared.

# File lib/mime/type.rb, line 154
def priority_compare(other)
  pc = simplified <=> other.simplified
  if pc.zero?
    pc = if (registered? != other.registered?)
           registered? ? -1 : 1 # registered < unregistered
         elsif (platform? != other.platform?)
           platform? ? 1 : -1 # generic < platform
         elsif (complete? != other.complete?)
           complete? ? -1 : 1 # complete < incomplete
         elsif (obsolete? != other.obsolete?)
           obsolete? ? 1 : -1 # current < obsolete
         elsif obsolete? and (use_instead != other.use_instead)
           if use_instead.nil?
             1
           elsif other.use_instead.nil?
             -1
           else
             use_instead <=> other.use_instead
           end
         else
           0
         end
  end

  pc
end
registered?() click to toggle source

Prior to BCP 178 (RFC 6648), it could be assumed that MIME content types that start with x- were unregistered MIME. Per this BCP, this assumption is no longer being made by default in this library.

There are three possible registration states for a MIME::Type:

  • Explicitly registered, like application/x-www-url-encoded.

  • Explicitly not registered, like image/webp.

  • Unspecified, in which case the media-type and the content-type will be scanned to see if they start with x-, indicating that they are assumed unregistered.

# File lib/mime/type.rb, line 401
def registered?
  if @registered.nil?
    (@raw_media_type !~ UNREGISTERED_RE) and
      (@raw_sub_type !~ UNREGISTERED_RE)
  else
    !!@registered
  end
end
signature?() click to toggle source

Returns true when the simplified MIME::Type is in the list of known digital signatures.

# File lib/mime/type.rb, line 429
def signature?
  !!@signature
end
system() click to toggle source

If the MIME::Type is a system-specific MIME::Type, returns the regular expression for the operating system indicated.

This information about MIME content types is deprecated.

# File lib/mime/type.rb, line 260
def system
  MIME.deprecated(self, __method__)
  @system
end
system?() click to toggle source

Returns true if the MIME::Type is specific to an operating system.

This method is deprecated.

# File lib/mime/type.rb, line 439
def system?
  MIME.deprecated(self, __method__)
  not @system.nil?
end
to_a() click to toggle source

Returns the MIME::Type as an array suitable for use with #from_array.

This method is deprecated.

# File lib/mime/type.rb, line 476
def to_a
  MIME.deprecated(self, __method__)
  [ @content_type, @extensions, @encoding, @system, obsolete?, @docs,
    @references, registered? ]
end
to_h() click to toggle source

Converts the MIME::Type to a hash suitable for use in JSON. The output of this method can also be used to initialize a MIME::Type.

# File lib/mime/type.rb, line 506
def to_h
  encode_with({})
end
to_hash() click to toggle source

Returns the MIME::Type as an array suitable for use with #from_hash.

This method is deprecated.

# File lib/mime/type.rb, line 486
def to_hash
  MIME.deprecated(self, __method__)
  { 'Content-Type'              => @content_type,
    'Content-Transfer-Encoding' => @encoding,
    'Extensions'                => @extensions,
    'System'                    => @system,
    'Obsolete'                  => obsolete?,
    'Docs'                      => @docs,
    'URL'                       => @references,
    'Registered'                => registered?,
  }
end
to_json(*args) click to toggle source

Converts the MIME::Type to a JSON string.

# File lib/mime/type.rb, line 500
def to_json(*args)
  to_h.to_json(*args)
end
to_s() click to toggle source

Returns the MIME::Type as a string.

# File lib/mime/type.rb, line 460
def to_s
  @content_type
end
to_str() click to toggle source

Returns the MIME::Type as a string for implicit conversions. This allows MIME::Type objects to appear on either side of a comparison.

'text/plain' == MIME::Type.new('text/plain')
# File lib/mime/type.rb, line 468
def to_str
  @content_type
end
urls() click to toggle source

The decoded URL list for this MIME::Type.

The special URL value IANA will be translated into:

http://www.iana.org/assignments/media-types/<mediatype>/<subtype>

The special URL value RFC### will be translated into:

http://www.rfc-editor.org/rfc/rfc###.txt

The special URL value DRAFT:name will be translated into:

https://datatracker.ietf.org/public/idindex.cgi?
    command=id_detail&filename=<name>

The special URL value [token] will be translated into:

http://www.iana.org/assignments/contact-people.htm#<token>

These values will be accessible through urls, which always returns an array.

# File lib/mime/type.rb, line 342
def urls
  references.map do |el|
    case el
    when %r{^IANA$}
      IANA_URL % [ @media_type, @sub_type ]
    when %r{^RFC(\d+)$}
      RFC_URL % $1
    when %r{^DRAFT:(.+)$}
      DRAFT_URL % $1
    when %r{^\{([^=]+)=([^\}]+)\}}
      [$1, $2]
    when %r{^\[([^=]+)=([^\]]+)\]}
      [$1, CONTACT_URL % $2]
    when %r{^\[([^\]]+)\]}
      CONTACT_URL % $1
    else
      el
    end
  end
end
use_instead() click to toggle source

Returns the media type or types that should be used instead of this media type, if it is obsolete. If there is no replacement media type, or it is not obsolete, nil will be returned.

# File lib/mime/type.rb, line 281
def use_instead
  return nil unless obsolete?
  @use_instead
end
xref_urls() click to toggle source

The decoded cross-reference URL list for this MIME::Type.

# File lib/mime/type.rb, line 364
def xref_urls
  xrefs.map { |(type, values)|
    case type
    when 'rfc'
      values.map { |data| "http://www.iana.org/go/#{data}" }
    when 'draft'
      values.map { |data|
        "http://www.iana.org/go/#{data.sub(/\ARFC/, 'draft')}"
      }
    when 'rfc-errata'
      values.map { |data|
        "http://www.rfc-editor.org/errata_search.php?eid=#{data}"
      }
    when 'person'
      values.map { |data|
        "http://www.iana.org/assignments/media-types/media-types.xhtml##{data}"
      }
    when 'template'
      values.map { |data|
        "http://www.iana.org/assignments/media-types/#{data}"
      }
    when 'uri', 'text'
      values
    end
  }.flatten
end